Forming corrugated hose



Sept. 24, 1968 J. w. DAVIDSON ET AL 3,402,429

FORMING CORRUGATED HOSE Original Filed Nov. 27, 1962 5 Sheets-Sheet 1wym ATTORNEYS p 1968 J. w. DAVIDSON ET AL 3,402,429

FORMING CORRUGATED HOS E Original Filed Nov. 27, 1962 5 Sheets-Sheet 227 I 8 2. yr 2 ATTORNEYS p 1963 J. w. DAVRDSON ET AL 3,402,429

FORMING CORRUGATED HOS E Original Filed Nov. 27, 1962 5 Sheets-Sheet 5l! H H n \\\\v////,\\\ /n/mwl'l FIG. 4

INVENTORS ATTORNEYS United States Patent 3,402,429 FORMING CORRUGATEDHOSE James W. Davidson, Willoughby, and John L. Maurer,

North Madison, Ohio, assignors to Eagle-Picher Industries, Inc.,Cincinnati, Ohio, a corporation of Ohio Original application Nov. 27,1962, Ser. No. 240,363, now Patent No. 3,333,036. Divided and thisapplication June 7, 1967, Ser. No. 644,155

4 Claims. (Cl. 18-19) ABSTRACT OF THE DISCLOSURE This applicationrelates to a mandrel free method of making a corrugated hose wherein thehose blank is gripped at both ends, stretched and then molded. Theapparatus for performing the process includes mold members, clampingmembers and means for operating said members.

This application is a division of our copending application Serial No.240,363 filed on Nov. 27, 1962, now US. Patent No. 3,333,036. Thepresent invention relates to shaping a hollow section of moldableplastic material and, more particularly, to mandrel-free method andapparatus for shaping, such as corrugating, a moldable tube in such amanner as to provide a medial portion of the tube having a wall sectionthat is thinner than a terminal portion.

Although the present invention encompasses various shaping operationsfor a hollow section of a moldable material, the invention isparticularly useful in corrugating a vulcanizable rubber tube.Accordingly, for convenience of disclosure, this shaping operation isreferred to in some detail. Heretofore, the practice of corrugating arubber tube has included the use of a mandrel which telescopicallyreceives the tube during the shaping or corrugating step. A mandrel wasconsidered necessary to support the uncured or unvulcanized materialuntil the material obtained sufiicient rigidity to be self-supporting. Amandrel, however, complicates the apparatus used and prolongs themolding operation in that each section of the moldable material must, atsome point in the process, be individually placed about the mandrel.Also, a mandrel generally restricts the length of the tube up to thelength of the mandrel, so that a variety of mandrels are usuallyrequired to meet diverse mandrels in a finished vulcanized tube.

The present invention obviates the need for a mandrel in the initialshaping or forming step to which the material which is to be shaped issubjected. Further, the invention provides a shaped tube or the likehaving a thicker wall section at a terminal, where the wear and strainare the greatest, then at a medial portion of the tube.

It is, therefore, a principal object to provide an improved method andapparatus for shaping a hollow section of moldable plastic material.

Another object is to provide such a method and apparatus which do notrequire a mandrel to support the section during a shaping orpre-creasing step.

A further object is to provide a method and apparatus of forming ahollow body having a terminal portion of greater wall thickness than amedial portion of the same body.

A still further object is to provide an apparatus for shaping a hollowsection of moldable plastic material which does not require a mandreland which in addition is readily adapted to forming different sectionsof varying lengths of the material.

Other objects of the invention will become apparent as the descriptionproceeds.

3,402,429 Patented Sept. 24, 1968 ice To the accomplishment of theforegoing and related ends, the invention consists of the featureshereinafter fully described and particularly pointed out in the claims,the annexed drawing and following disclosure describing in detail theinvention, such drawing and disclosure illustrating, however, but one ormore of the various ways in which the invention may be practiced.

In the accompanying drawings:

FIGURES 1 and 2 are front and side elevational views, respectively, ofone form of the present apparatus;

FIGURE 3 is a section of FIGURE 1 on the line 3-3 but illustrates themold parts in open position;

FIGURE 4 is a bottom plan view of FIGURE 3 on the line 44;

FIGURE 5 is a fragmentary longitudinal section of the left-hand clamp orchuck, as viewed in FIGURE 1, used to grip an end of a hollow section tobe shaped;

FIGURE 6 is a side elevational view of a tube shaped in accordance withthe present invention and ready for curing;

FIGURE 7 is a longitudinal section of the tube of FIGURE 6 after cure;and

FIGURES 8 and 9 are diagrammatic illustrations of the effect ofrelatively moving the end clamps to reduce the gauge of a gripped tube.

General description Instead of a mandrel which telescopically receives ahollow moldable section, such as in the form of a tube, clamping orgripping means are used in the present invention to engage the ends ofthe tube. The tube or like workpiece is otherwise unsupported. In oneform, the clamps or other means move axially with respect to each otherbeyond the travel of mold sections traversed by the sections uponclosing by the tube to mold it as desired. Usually fluid under pressureenters the tube and forces it against the mold walls to effect themolding operation.

In the case of forming a corrugated hose or the like, the mold sectionsform axially-spaced circumferential creases in the tube. Upon reopeningthe mold, the tube is axially compressed by folding it along theprecreases. Finally, the tube is cured or vulcanized in the axiallycompressed state.

Certain advantages result from this omission of a mandrel. The endportions of the tube or like hollow workpieces that are gripped by theclamps retain their original thickness or gauge throughout the operationportion of the tube. Or, as a further modification, successivereductions in wall thickness of the medial portion by both of thesetechniques may be obtained.

The net result is that for a given weight of raw stock it is possible toobtain a longer hose still having ends or terminals of a requisitethickness. Or the same length of hose may be realized as under priortechniques but having thicker end collars. The obtaining of thicker endsby either route is significant because the severest wear on a tube, andespecially a corrugated tube, is at the very ends where the tube istightly held after installation.

A still further advantage resulting from the present invention is theomission of a trimming operation on the finished product. Because theends of the tube can initially be cut as desired from the raw stock andare cured or vulcanized in this desired shape, the desired configurationof the hose terminals are formed automatically. It is accordingly notnecessary to trim the finally produced hose or tube as is nowcustomarily the practice.

Apparatus Referring particularly to FIGURES 1 through 5, the form of theapparatus illustrated includes a frame generally indicated at F having ahorizontally disposed overhang H to which is suitably secured astationary bedplate 10. Along the base B of the frame, a pair ofU-shaped platforms 11 and 12, integral with the frame, have theterminals of piston rods 13 and 14, respectively, fixed thereto. Fluidactuated cylinders 15 and 16 receive the piston rods at their lower endsand are fixed at their upper ends to a movable bedplate 17. The latterhas U-shaped riders 18 at each end which during vertical reciprocationof the bedplate 17 by the cylinders 15 and 16 slidingly grip riderplates 19 fixed at the sides of the frame F.

FIGURES 3 and 4 illustrate the relation between and structure of thestationary bedplate 10 and the movable bedplate 17 and attendant moldparts. Each bedplate has a channel 20 having laterally projectingflanges 21 contacting a bedplate. Strips 22 suitably fixed to a bedplateas by welding extend along the flanges 21. Hold-down lugs 23 and bolts24 tightly contact the flanges 21 to lock each channel 20 at a desiredlocation on a bedplate. This arrangement also permits adjustment in allhorizontal directions as may be desired.

The actual molding implements are held within the channels 20. In thecase of molding a corrugated tube, the shaping implements include aseries of solid, hard, elastic rubber segments 25, eachsegment having aplurality of semicircular ridges 25a. The segments 25 are aligned(FIGURE 4) for a desired length along each bedplate 10 and 17. The useof stacked segments as illustrated permits bleeding of air from the moldbetween such segments during a molding operation. For this purpose also,the roots or valleys between each convolution 25a may have a bleed hole26. Normally, the segments 25 of the two bedplates are verticallyaligned, so that closing the two mold sections uniformly creases a tubecircumferentially at axially spaced points. Instead of spaced creases, aspiraling crease or still other configurations can obviously beemployed.

A pair of clamps or chucks 27 and 28 are stationed at opposite ends ofthe cooperating bedplates 10 and 17. When the mold parts are closed, theoverall vertical width is not very great. Accordingly, in order toprovide for an operator sufficient room in which to load and unload theapparatus, means are included to permit vertical travel of the clamps 27and 28 so that these clamps have a floating relation between the closingmold sections. In this way, the clamps are not clamped near either moldsection and, in fact, occupy a vertical position midway of the moldparts when they are in an open station.

More particularly, with respect to clamp 27, a slide plate 29 which maybe offset (FIGURE 2), has longitudinally disposed slots 30 that freelyengage pins 31 on both bedplates 10 and 17. Heads on the pins retain theplate 29 in assembly. The plate 29 carries a fixed block 32 which inturn has an opening to receive and support a rod 33 forming part of theclamp 27 (FIGURE 5). The rod 33 has a longitudinal bore 34 to admitfluid, as hereinafter described, and terminates in a reduced portion 35of smaller diameter having a rounded nose N of still smaller diameter.An annular sleeve 36 fits about this rod terminus and has a shoulder 37to form in cooperation with the reduced portion of the rod an annularhousing for a coiled spring 38. The sleeve 27 also has an inwardlyextending lip 39 which cooperates with the nose N to grip therebetweenthe end of a tube T or other like workpiece.

A second slide plate 40 supports the clamp 28. This slide plate also haslongitudinally disposed slots 41 freely engaging headed pins 42 on bothof the bed-plates 10 and 17.The structure of clamp 28 is the same asclamp 27,

. except that a rod 43 (corresponding to rod 33) does not 4 to the slideplate 40 (FIGURE 1) which has an opening to accommodate the horizontalreciprocal movement of the rod 43.

Operation In operation, with the mold sections in separated openposition, cylinder 44 which is conventionally operated as by compressedair moves clamp 28 toward clamp 27 so that the clamps are a distanceapart which is no greater than the length of the tube T of raw stockwhich is to be processed. An operator backs-off the sleeve 36 of eachclamp, fits a tube end over the nose N, and allows the sleeve to returnso that the tube ends are tightly gripped. FIGURE 8 diagrammaticallyillustrates the relative positions of the clamp and tube at this time.

Cylinder 44 now retracts clamp 28 bringing the tube T into linearalignment and preferably also tensioning and/or stretching the tube todecrease the wall thickness of the nongripped part. FIGURE 9 illustratesthe relative positions of the clamp and tube at this time. It will benoted that the wall of the tube T in FIGURE 9 has a smaller thicknessthan in FIGURE 8. However, the thickness or gauge of the ends of thetube within the grip of the clamps 27 and 28 is not substantiallychanged. The stroke of the cylinder 44 is adjusted to place the clamps27 and 28 beyond the area of movement of the bedplate 17 and preferablyjust beyond that area so that most of the tube T is within the strokearea of that bedplate.

The cylinders 15 and 16, which may be conventionally hydraulicallyoperated, now lift the bedplate 17. There is no vertical movement of theclamps 27 and 28 until the pins 31 of the lower bedplate 17 reach theupper ends of the lower slots in the slide plates 29 and 40 as viewed inFIGURE 1. Thereafter, the clamps are lifted vertically also and continueto rise until the pins 31 of the upper bedplate 10 reach the lower endsof the upper slots in the slide plates 29 and 40 as viewed in FIGURE 1.At this time the mold sections have closed about the tube T and theclamps and attendant apparatus are in operative molding position. Airunder pressure is next conventionally admitted through a conduit 45 andthrough the bore 34 of the rod 33 in clamp 27 to expand the tube Tagainst the walls of the mold as defined by the encompassing segments25. Thereafter, cylinders 15 and 16 lower the bedplate 17 and clamps 27and 28 in reverse order to that described until the starting positionsare reached. The operator may then remove the molded tube from theclamps.

In the case of molding a heat-curable material, such as vulcanizablerubber, the above operation usually does not set the material, since theoperation is substantially cold and may last only three to sevenseconds. If desired, heating means can be stationed about the molds tocure the material simultaneously with the passing operation, the moldremaining closed during this time. This technique, however, ties up themolding equipment and accordingly it is much preferred to cure thematerial externally of the molding apparatus.

For example, in the case of making a corrugated tube, after removal fromthe mold the substantially uncured tube is axially compressed accordionfashion along the creases imparted by the molding operation and thencured while held in this compressed state. In one embodiment, the moldedtube T is placed about a short mandrel 46 for the first time and held inan axially compressed state by rings 47 abutting the ends of the tubeand fixed to the mandrel by set screws 48 (FIGURE 6). This assembly isplaced in an oven, autoclave, or the like and heated to set the materialsuch as by vulcanization. After removal from the oven, the tube T iselastic and easily retains its shape. No trimming is necessary. Such acured product is illustrated by FIGURE 7 which also shows the endterminals 49 having a thicker gauge than that of a medial portion 50 ofthe tube. In one instance, a tube of predetermined length produced bythis invention weighed 26 percent less than a tube of equal length andcomposed of the same material but produced by prior art techniques.

Also the clamp 27 has been described as stationary (except for verticalmovement) and in the embodiment described is, in fact, stationary for agiven operation. Clamp 27 is nonetheless capable of being adjusted in ahorizontal direction along the bedplates 1G and 17. It is necessary onlyto relocate the pins 31 as desired, the pins being threaded and engagingselectively suitably threaded openings along the edges of the bedplates.To illustrate this, clamp 27 and slide plate 29 have been locatedinwardly from the lefthand end of the apparatus as viewed in FIG- URE l.Thus, quite independently of any limiting mandrel size, a large varietyof tubular sections differing in length and diameter may be processed bythe same versatile apparatus.

We claim:

1. Apparatus for shaping a generally tubular section of deformableplastic material including a fixed elongated mold section, a movableelongated mold section cornplernentary to the first, means toreciprocate the movable mold section toward and away from the fixed moldto close and open the mold formed by said sections and thereby define anarea of movement, a pair of clamp means supported with respect to thefixed mold section for movement toward and away from said fixed moldsection, each clamp means being adapted to grip an end portion of thetubular section sufficiently tightly to resist stretching forces tendingto reduce the thickness of the wall of such gripped portion, means tomove the clamp means relatively apart in a direction angularly to thedirection of movement of the movable mold section and beyond said areaof movement to stretch the tubular section so gripped, means carried bysaid movable mold section and by said fixed mold section to move saidclamp means vertically when said movable mold section moves vertically,and means to ad mit fluid under pressure through one clamp meansefiective to expand a gripped tubular section to the confines of theclosed molds.

2. Apparatus for shaping a hollow section of deformable plastic materialincluding complementary elongated mold parts, means to reciprocate themold parts relatively between opened and closed stations, suchreciprocation defining an area of movement, clamp means to grip an endportion of each end of the hollow section sufficiently tightly to resiststretching forces tending to reduce the thickness of the wall of suchgripped portion, means to move the clamp means relatively apart in adirection angularly to the direction of movement of the mold parts andbeyond said area of movement to stretch the hollow sec tion so gripped,means carried by said movable mold section and by said fixed moldsection to move said clamp means vertically when said movable moldsection moves vertically, and means to admit fluid under pressurethrough one clamp means eifective to expand a gripped section of thedeformable plastic material to the confines of the closed mold parts.

3. Apparatus for shaping a hollow plastic section includingcomplementary mold parts mounted for relative movement between openedand closed poistions to define a stroke area, gripping means forgripping ends of the section while leaving a medial portion thereofunsupported mounted for relative axial movement within such stroke area,means to move the gripping means relatively apart and beyond the strokearea, means carried by said movable mold section and by said fixed moldsection to move said clamp means vertically when said movable moldsection moves vertically, and means to admit fluid through one of thegripping means.

4. Apparatus for shaping a hollow plastic section including grippingmeans for gripping ends of the section while leaving a medial portionthereof unsupported, mold parts stationed in open position about thegripping means and adapted to move toward said means upon closing, meansto move the gripping means relatively apart and beyond the closingstroke of the mold parts to bring the unsupported medial portion of theplastic section into a linear disposition engageable by the closing moldparts, means carried by said movable mold section and by said fixed moldsection to move said clamp means vertically when said movable moldsection moves vertically, and means to expand the mold-engaged tube intoconformity with said closed mold parts.

References Cited UNITED STATES PATENTS 2,401,728 6/1946 Gillette et a118-19 2,866,230 12/1958 Holte 18--19 2,897,840 8/ 1959 Roberts et a1.2,999,272 12/ 1961 Warnken 18-19 FOREIGN PATENTS 1,254,690 l/1961France.

WILLIAM J. STEPHENSON, Primary Examiner.

